The present invention relates to a configuration of a switching system and a switching control method. More particularly, the invention relates to a switching system, which is suitably used for processing plural kinds of media (voice/image/data) communicated by a variety of media at various speeds, and a control method thereof.
In today's digital communication network, each medium of a voice, an image or data is communicated through a variety of communication networks. For example, these communication networks may include the following: (1) a packet communication network for performing communications by carrying signals on variable length packets, which is described in “Basic Knowledge on Data Exchange” issued by The Telecommunications Association (TTA); (2) a Synchronous Transfer Mode (STM) communication network for performing communications by carrying signals in time slots divided by time in a synchronized frame, which is described in “Easy Digital Switching” also issued by TTA; (3) an Asynchronous Transfer Mode (ATM) communication network for performing communications by carrying signals on fixed-length packets called cells, which is described in “B-ISDN Reader with Pictures” issued by Ohmsha, Ltd.; and (4) an IP communication network (Internet) for performing IP packet communications by carrying signals on variable length packets called IP packets in accordance with a procedure called an Internet Protocol (IP), which is described in “Mastering TCP/IP” also issued by Ohmsha, Ltd. Regarding media for transmitting signals, in addition to a conventional cable medium using such as a metallic cable, an optical fiber or the like, use of media for transmitting signals by radio has rapidly increased as in the case of a mobile communication network, which is described in “Mobile Communication System” issued by Science Newspaper Publishing Company. For such a mobile communication network, various types have been developed: e.g., Personal Digital Cellular (PDC) and Personal Handyphone System (PHS) communication networks for performing communications by carrying signals in time slots as in the case of the STM communication network described in “Mobile Communication Handbook” issued by Ohmsha, Ltd., a Code Division Multiple Access (CDMA) communication network for performing communications by modulating signals with codes different among the signals, which is described in “Easy Digital Mobile Communication” issued by TTA, and so on.
The foregoing existing communication networks and communication systems have been independently developed/introduced. Thus, there are differences in signal formats (speeds, formats) or communication procedures (signal systems, protocols or the like). There are also differences in characteristics among the communication networks. As a result, differences exist in communication services to be rendered, control mechanisms for providing such services (e.g., operation system configurations, hardware/software interface configurations, communication application software functions and configurations) or the like.
Under these circumstances, requests have been made by communication network users that transmit/receive information by using communication networks and providers that provide such communication networks. These requests are as follows: the foregoing differences among the networks should be eliminated (or absorbed), and they can carry out communications with opposite parties by using communication services capable of transmitting information in an optimal state without being conscious of configurations or procedures of the communication networks, whenever they wish and by any devices (stations) they wish to use. If such requests are met, operation convenience of communication facilities will be improved, and communication costs will be reduced. These will contribute to development of the society.
Thus, as described in “General Information about CTRON-Introduction and Common Rules” issued by TRON Association, studies have been made for establishing an integrated communication network, which enables the plural kinds of media (voice/image/data) and communication networks (STM/ATM or cable/radio) to be processed in an integrated manner. Thus far, however, only partial media have been integrated and processed, and the establishment of an integrated communication network has not been completed yet. In addition to the communication network integrating a variety of communication networks, requests have been made to provide a communication network/communication device (mainly a switching system) capable of performing inter-working among the networks, which enables communications to be carried out by absorbing differences among the communication networks and making interconnections with simple control, and also to provide a control method thereof.
Application software developed for each communication network is precious property of communication network's (developer's) own, which has been developed by an enormous amount of time and labor. There is thus a desire to use the application software as it is even if a change occurs in a hardware configuration or a basic software configuration. In other words, continued use of existing application software is desired, even if inter-working is carried out among the plurality of communication networks.